Answer: Bacteria
Notes: Lyme disease, affecting about 476,000 people annually in the US, is caused by the bacterium Borrelia burgdorferi and spread through bites from infected black-legged ticks. It cannot be transmitted between humans or through other insects. Symptoms appear 3 to 30 days after a tick bite, including fever, headache, fatigue, and a "bull's-eye" rash. If untreated, it can lead to serious complications, but early-stage cases are effectively treated with antibiotics like doxycycline or amoxicillin.
